Noninvasive prenatal detection of sex chromosomal aneuploidies by sequencing circulating cell-free DNA from maternal plasma.

Objective: Whole-genome sequencing of circulating cell free (ccf) DNA from maternal plasma has enabled noninvasive prenatal testing for common autosomal aneuploidies. The purpose of this study was to extend the detection to include common sex chromosome aneuploidies (SCAs): [47,XXX], [45,X], [47,XXY], and [47,XYY] syndromes.

Method: Massively parallel sequencing was performed on ccf DNA isolated from the plasma of 1564 pregnant women with known fetal karyotype.

The impact of maternal plasma DNA fetal fraction on next generation sequencing tests for common fetal aneuploidies.

Maternal plasma contains circulating cell-free DNA fragments originating from both the mother and the placenta. The proportion derived from the placenta is known as the fetal fraction. When measured between 10 and 20 gestational weeks, the average fetal fraction in the maternal plasma is 10% to 15% but can range from under 3% to over 30%.

High-throughput massively parallel sequencing for fetal aneuploidy detection from maternal plasma.

Background: Circulating cell-free (ccf) fetal DNA comprises 3-20% of all the cell-free DNA present in maternal plasma. Numerous research and clinical studies have described the analysis of ccf DNA using next generation sequencing for the detection of fetal aneuploidies with high sensitivity and specificity. We sought to extend the utility of this approach by assessing semi-automated library preparation, higher sample multiplexing during sequencing, and improved bioinformatic tools to enable a higher throughput, more efficient assay while maintaining or improving clinical performance.

Feasibility of using plasma rather than serum in first and second trimester multiple marker Down's syndrome screening.

Objective: To compare maternal plasma with serum for measuring markers currently used in first and second trimester screening for Down's syndrome.

Setting: A laboratory-based investigation of two sample types in assays used in prenatal screening for Down's syndrome.

Methods: A paired data-set included both plasma and serum from 101 pregnant women.

Impact of adjusting for the reciprocal relationship between maternal weight and free thyroxine during early pregnancy.

Background: Among euthyroid pregnant women in a large clinical trial, free thyroxine (FT4) measurements below the 2.5th centile were associated with a 17 lb higher weight (2.9 kg/m(2)) than in the overall study population.

DNA sequencing of maternal plasma to identify Down syndrome and other trisomies in multiple gestations.

Objective: Studies on prenatal testing for Down syndrome (trisomy 21), trisomy 18, and trisomy 13 by massively parallel shotgun sequencing (MPSS) of circulating cell free DNA have been, for the most part, limited to singleton pregnancies. If MPSS testing is offered clinically, it is important to know if these trisomies will also be identified in multiple pregnancies.

Method: Among a cohort of 4664 high-risk pregnancies, maternal plasma samples were tested from 25 twin pregnancies (17 euploid, five discordant and two concordant for Down syndrome; one discordant for trisomy 13) and two euploid triplet pregnancies [Correction made here after initial online publication.

DNA sequencing of maternal plasma reliably identifies trisomy 18 and trisomy 13 as well as Down syndrome: an international collaborative study.

Purpose: To determine whether maternal plasma cell-free DNA sequencing can effectively identify trisomy 18 and 13.

Methods: Sixty-two pregnancies with trisomy 18 and 12 with trisomy 13 were selected from a cohort of 4,664 pregnancies along with matched euploid controls (including 212 additional Down syndrome and matched controls already reported), and their samples tested using a laboratory-developed, next-generation sequencing test. Interpretation of the results for chromosome 18 and 13 included adjustment for CG content bias.

DNA sequencing of maternal plasma to detect Down syndrome: an international clinical validation study.

Purpose: Prenatal screening for Down syndrome has improved, but the number of resulting invasive diagnostic procedures remains problematic. Measurement of circulating cell-free DNA in maternal plasma might offer improvement.

Methods: A blinded, nested case-control study was designed within a cohort of 4664 pregnancies at high risk for Down syndrome.

Prenatal screening for trisomy 21: recent advances and guidelines.

The performance of prenatal screening tests for the identification of trisomy 21 (Down syndrome) has markedly improved since the 1970s and early 1980s when maternal age was the sole mode of screening the general pregnant population. With the discovery of second trimester serum markers in the 1980s and 1990s and implementation of double, triple, and quad marker testing; the discovery of first trimester serum and ultrasound markers in the 1990s and implementation of the combined test; and the development of the integrated test and sequential screening strategies over the past decade, the performance of screening has improved to a detection rate of 90%–95% at a false positive rate of 2%–5%. In this review, I will describe the advances in prenatal screening for trisomy 21, present current screening strategies, and discuss guidelines published by professional societies and regulatory bodies, with a focus on current prenatal screening practice in the USA.

The relationship between PTH and 25-hydroxy vitamin D early in pregnancy.

Objective: Measure serum PTH and 25(OH)D in a cross-sectional sample of pregnant women at 11th through 13th weeks' gestation to examine vitamin D status and consider implications.

Design: Observational: we retrieved residual sera stored at -20 °C after routine first trimester Down's syndrome screening, distributed over 12 months.

Patients: 430 African American women and 586 Caucasian women.

Impact of smoking on maternal serum markers and prenatal screening in the first and second trimesters.

Objectives: To examine the effects of smoking on first and second trimester screening markers and to determine the overall impact of these effects on Down syndrome and trisomy 18 risks in first trimester combined, second trimester quadruple and integrated tests.

Methods: Examination of screening records at Women and Infants Hospital during 2006-2008. First trimester pregnancy-associated plasma protein-A (PAPP-A), beta-human chorionic gonadotrophin (hCG) and nuchal translucency and second trimester alpha-fetoprotein (AFP), unconjugated estriol (uE3), hCG and inhibin A (inhA) multiple of the median (MoM) values were extracted from the database along with risk results, smoking status and relevant demographic information.

Thyroperoxidase and thyroglobulin antibodies in early pregnancy and placental abruption.

Objective: To estimate the relationship between thyroid antibodies and placental abruption.

Methods: This cohort study assesses thyroperoxidase and thyroglobulin antibodies in relation to placental abruption among 10,062 women with singleton viable pregnancies (from the First and Second Trimester Risk of Aneuploidy [FaSTER] trial). A thyroperoxidase antibody cutoff of 50 international units/mL is used for comparison with published data from another cohort.

Adjustment of maternal serum alpha-fetoprotein levels in women with pregestational diabetes.

Objective: Decreased second trimester levels of maternal serum alpha-fetoprotein (MSAFP) have been reported in women with pregestational diabetes leading some laboratories to use a correction factor. The aim of this study is to determine if MSAFP levels in pregnant women with diabetes managed on oral antidiabetic agents is lower than non-diabetic controls and require adjustment similar to those on insulin.

Study Design: We performed a nested case/control study of an existing dataset using women with pregestational diabetes who had routine MSAFP values available.

Four years' experience with an interlaboratory comparison program involving first-trimester markers of Down syndrome.

Context: We initiated a voluntary, self-funded interlaboratory comparison program in the fall of 2005 because no proficiency testing program was available to laboratories in North America offering first-trimester, combined serum and ultrasound, Down syndrome screening. Objectives.-To evaluate the first 4 years of the interlaboratory comparison program against stated goals, to identify areas of concern, and to create new initiatives as indicated.

Examination of the pregnancy-associated plasma protein-A assay on the Beckman Coulter Access(®) platform: suitability for use in first trimester Down's syndrome screening.

Objective: To explore the clinical validity of the new Access(®) pregnancy-associated plasma protein-A (PAPP-A) assay for Down's syndrome screening.

Setting: Academic hospital.

Method: Residual serum samples (n = 416) received for routine first trimester Down's syndrome screening (10-13 weeks) were retrieved from freezer storage and tested using two PAPP-A immunoassay methods.

Thyroperoxidase and thyroglobulin antibodies in early pregnancy and preterm delivery.

Objective: To further evaluate the relationship between thyroid antibodies and preterm births.

Methods: This is a prospective study of pregnancy outcome and demographic data combined with retrospective measurement of thyroperoxidase and thyroglobulin antibodies. Sera were obtained at 11-13 and 15-18 weeks of gestation from 10,062 women with singleton viable pregnancies (a subset from the First- and Second-Trimester Risk of Aneuploidy [FaSTER] trial).

Early onset preeclampsia and second trimester serum markers.

Objective: To examine serum markers measured in the second trimester to identify women who subsequently develop preeclampsia.

Methods: Clinically defined preeclampsia was confirmed in 45 women who had provided a serum sample as part of Down syndrome screening. Preeclampsia was categorized as mild or severe, as well as early (<32 weeks) or late onset.

Technical standards and guidelines: prenatal screening for Down syndrome that includes first-trimester biochemistry and/or ultrasound measurements.

This statement is intended to augment the current general ACMG Standards and Guidelines for Clinical Genetics Laboratories and to address guidelines specific to first-trimester screening for Down syndrome. The aim is to provide the laboratory the necessary information to ensure accurate and reliable Down syndrome screening results given a screening protocol (e.g.

Adjustment of serum markers in first trimester screening.

First trimester combined screening can be performed using maternal serum pregnancy-associated plasma protein A, total human chorionic gonadotropin (hCG) and ultrasound measurement of nuchal translucency at 11-13 weeks of pregnancy. Our objective was to explore the effects of covariates on total hCG in the first trimester. First trimester total hCG levels were significantly increased in twins (median = 1.

Maternal thyroid hypofunction and pregnancy outcome.

Objective: To estimate whether maternal thyroid hypofunction is associated with complications.

Methods: A total of 10,990 patients had first- and second-trimester serum assayed for thyroid-stimulating hormone (TSH), free thyroxine (freeT4), and antithyroglobulin and antithyroid peroxidase antibodies. Thyroid hypofunction was defined as 1) subclinical hypothyroidism: TSH levels above the 97.

First- and second-trimester thyroid hormone reference data in pregnant women: a FaSTER (First- and Second-Trimester Evaluation of Risk for aneuploidy) Research Consortium study.

Objective: The purpose of this study was to calculate first and second trimester reference ranges and within-woman correlations for TSH, free T4, and thyroid antibodies.

Study Design: TSH, free T4, and thyroid antibodies were measured in paired sera from 9562 women in the FaSTER trial of Down syndrome screening.

Results: The median first trimester TSH (1.

Variability in thyroid-stimulating hormone suppression by human chorionic [corrected] gonadotropin during early pregnancy.

Objective: The objective of the study was to further explore relationships between human chorionic gonadotropin (hCG), TSH, and free T4 in pregnant women at 11 through 18 wk gestation.

Study Design: The design of the study was to analyze hCG in comparison with TSH and free T4, in paired first- and second-trimester sera from 9562 women in the First and Second Trimester Evaluation of Risk for Fetal Aneuploidy trial study.

Results: hCG is strongly correlated with body mass index, smoking, and gravidity.